The present invention relates to a control system for an intraocular surgical device and in particular for use with a device for vitrectomy.
Various devices have been proposed to cut and suck vitreous from the eye of a patient suffering from certain diseases, trauma or endoocular complications. Devices of this type are well known as vitreous cutters.
Vitreous cutters basically comprise a blade and a motor of either the electrical or pneumatic type which moves the blade. The control of the cutter is carried out by a control system which is in turn under the control of the opthamalogical surgeon.
While in the past the small vitreous cutters were activated by a small DC motor or by a magnetic solenoid, U.S. Pat. Nos. 3,815,604 and 3,884,238 disclosed a pneumatically activated cutter which made use of a gas under pressure to start the cutter in operation.
The pneumatic cutter constitutes a significant advance over the DC or magnetic solenoid actuated type, however it was found that the control systems disclosed in the aforementioned U.S. patents have several disadvantages which may cause problems during surgery.
For example, the control system disclosed therein requires a small compressor to be built into the console which developes only a few psi of positive pressure and vacuum for actuating the cutter. The cutting force is therefore very limited and during the surgery the blade may easily block causing problems for the surgeon.
Moreover, the blade must move back and forth to effect cutting and the movement in one direction is due to the positive pressure created by the compressor, while the movement in the other direction is created by the elastic action of the bellows and the depressure created by the compressor. As a result, the force which is used in the backward movement is very small and creates problems during surgery since the blade has its cutting action only when it is activated in the forward direction. This limits the type of blades which can be used.